Transmission of control information using more than one beam pair link
One way to increase robustness against beam pair link failure is by transmitting downlink (DL) control signaling (e.g., PDCCH) in more than one beam. That is, one way to mitigate BPLF is for the UE to receive DL control signaling over both a first BPL (e.g., active BPL) and a second BPL (e.g., monitored BPL) but with larger duty cycle for the second BPL compared to the first BPL. For example, the control signaling can be scheduled every slot on the first BPL and scheduled every Nth slot on the second BPL. In this way, in case the first BPL is blocked and the UE cannot decode the control signaling on the first BPL, the UE can receive control signaling transmitted on the second BPL.
1. A method performed by one or more transmission points (TRPs) communicating with a user equipment (UE), the method comprising:
defining a first search space and a second search space, wherein a first transmit (TX) beam is associated with the first search space and a second TX beam is associated with the second search space;
for a transmission of a control channel candidate to the UE, selecting the first or second search space; and
transmitting the control channel candidate in control channel resources belonging to the selected search space using the TX beam associated with the selected search space, wherein
the first search space is a first portion of a control area of a first subframe that has a data area that is separate from the control area of the first subframe, and
the second search space is a second portion of the control area of said first subframe or the second search space is a portion of a control area of a second subframe.
2. The method of claim 1 , where the first TX beam is related to a first BPL and the second TX beam is related to a second BPL.
3. The method of claim 2 , where the selection is based on information that the first BPL has experienced a beam pair link failure.
4. The method of claim 2 , wherein
the second search space is a second portion of the control area of said first subframe.
5. The method of claim 4 , wherein
the first portion of the control area and the second portion of the control area overlap in time at least partially, or
the first portion of the control area does not overlap in time with the second portion of the control area.
6. The method of claim 2 , wherein
the first search space is the control area of the first subframe, and
the second search space is the control area of the second subframe.
7. A transmission point (TRP), the TRP comprising:
a transmitter,
a receiver,
a memory, and
a data processing system comprising one or more processors, wherein the TRP is configured to perform the method of claim 1 .
8. A method performed by a user equipment (UE) communicating with one or more transmission points (TRPs), the method comprising:
the UE using a first set of one or more quasi co-location (QCL) parameters for receiving a control channel candidate in a first search space; and
the UE using a second set of one or more QCL parameters for receiving a control channel candidate in a second search space, wherein,
the first search space is a first portion of a control area of a first subframe that has a data area that is separate from the control area of the first subframe, and
the second search space is a second portion of the control area of said first subframe or the second search space is a portion of a control area of a second subframe.
9. The method of claim 8 , wherein
the second search space is a second portion of the control area of said first subframe.
10. The method of claim 9 , wherein
the first portion of the control area and the second portion of the control area overlap in time at least partially, or
the first portion of the control area does not overlap in time with the second portion of the control area.
11. The method of claim 8 , wherein
the first search space is the control area of the first subframe, and
the second search space is the control area of the second subframe.
12. The method of claim 8 , wherein at least one of the QCL parameters in each of the first and second sets of QCL parameters is a spatial QCL parameter.